Electrochemical quantification and sorptive removal of zinc and cadmium using natural apophyllite zeolite by differential pulse polarography

Abstract

The increasing threat of heavy metal pollution, particularly from zinc and cadmium, necessitates the development of sensitive, cost-effective, and eco-friendly remediation and detection strategies. This study investigates the dual application of natural apophyllite zeolite for the sorptive removal and electrochemical quantification of Zn²⁺ and Cd²⁺ ions using Differential Pulse Polarography (DPP). Apophyllite, characterized by its porous crystalline structure and ion exchange capacity, was evaluated through batch adsorption studies under varying pH, contact time, adsorbent dose, metal ion concentration, and temperature. Electroanalytical optimization revealed 1.5 M KCl at pH 2.0 as the most suitable supporting electrolyte for DPP, with well-defined peak potentials for cadmium (-0.66 V) and zinc (-1.034 V). Instrumental parameters such as scan rate and pulse amplitude were optimized, yielding limits of detection (LODs) of 0.809 ppm for Cd and 1.164 ppm for Zn. Adsorption data provided insight into the Total Exchange Sorption Capacity (TESC), distribution coefficient (K), and percent recovery (ε), confirming high removal efficiency. The results demonstrate that apophyllite serves as both an effective adsorbent and an electrochemical matrix modifier, offering a green analytical platform for trace-level monitoring and remediation of toxic metals in environmental matrices.